I've recently picked up some 5E books (first time reading through them this week), and thought it might be nice to try and describe some of the things in the Mystara 2300 BC Adventure Path (Engdyr's Game) coming in upcoming issues of Threshold (starting with Threshold #16). Anyway, I thought I'd start by trying to come up with some custom race pics for the campaign setting (specifically races found in the Shimmering Lands circa BC 2300). As I'm still new to 5E these are incomplete, and may be a bit wonky), so I welcome input from others.

Design Notes: Dwarves from the 2300 BC setting are not the same dwarves seen in modern era Mystara. These are the dwarves before Kagyar changed then to the "Rockborn" in BC 1800, and as such I wanted to create a very different flavor for them.
Alignment changed from Lawful Good to Chaotic Neutral.
Changed base ability score from Constitution to Intelligence and shifted focus to sub-races. Dwarves in this era suffer from the effects of the Wasting, and this is one thing that Kagyar changed about them in BC 1800. It is only after that change that dwarves become more resilient.
Darkvision, Dwarven Resilience, and Stonecunning have been removed from the base racial traits, and will be replaced by traits more specific to each sub-race. The original dwarven racial traits are more in line with the changes that Kagyar will make in BC 1800, and so are not present in this era’s dwarven population.

Your dwarf character has an assortment of inborn abilities, part and parcel of dwarven nature.

Ability Score Increase. Your Intelligence score increases by 1.

Age. Dwarves mature at the same rate as humans, but they’re considered young until they reach the age of 50. On average, they live about 350 years.

Alignment. Most dwarves are chaotic, and extremely individualistic believing that they are the center of their own universe and that all of creation should serve them. They tend toward neutral, preferring to mind their own business and expecting that others do the same.

Size. Dwarves stand between 4 and 5 feet tall and average about 150 pounds. Your size is Medium.

Languages. You can speak, read, and write Common and Dwarvish. Dwarvish is full of hard consonants and guttural sounds, and those characteristics spill over into whatever other language a dwarf might speak.

Yardrak
Thanks to pacts that the Yardrak made with dark entities, your resilience and ability to cope with the Wasting has improved greatly.
[These guys are essentially supposed to be the Mystara BC 2300 version of tieflings. Their ancestors made pacts with dark forces in order to survive the GRoF and its Wasting disease. While most other dwarves end being sickly (no Con bonus), these guys are fairly robust... but they also manifest some aspect of their dark heritage (red skin, demon eyes, forked tongue, etc...)]

Ability Score Increase. Your Constitution score increases by 2.

Hellish Resistance. You have resistance to fire damage.

Infernal Legacy. You know the thaumaturgy cantrip. When you reach 3rd level, you can cast the hellish rebuke spell as a 2nd level spell once with this trait and regain the ability to do so when you finish a long rest. When you reach 5th level, you can cast the darkness spell once with this trait and regain the ability to do so when you finish a long rest. Intelligence is your spellcasting ability for these spells.

Felwig
Felwig dwarves are known as the inheritors of Blackmoor’s legacy, and are adept at using ancient lore and technologies.
[These guys are essentially re-skinned rock/tinker gnomes. As there are also gnomes in this setting, I want to find some way of distinguishing the two races, so this will probably continue to evolve - for example "Music Box" doesn't seem very dwarven to me.]

Artificer’s Lore. Whenever you make an Intelligence (History) check related to magic items, alchemical objects, or technological devices, you can add twice your proficiency bonus, instead of any proficiency bonus you normally apply.

Tinker. You have proficiency with artisan’s tools (tinker’s tools). Using those tools, you can spend 1 hour and 10 gp worth of materials to construct a Tiny clockwork device (AC 5, 1 hp). The device ceases to function after 24 hours (unless you spend 1 hour repairing it to keep the device functioning), or when you use your action to dismantle it; at that time, you can reclaim the materials used to create it. You can have up to three such devices active at a time. When you create a device, choose one of the following options:Clockwork Toy. This toy is a clockwork animal, monster, or person, such as a frog, mouse, bird, dragon, or soldier. When placed on the ground, the toy moves 5 feet across the ground on each of your turns in a random direction. It makes noises as appropriate to the creature it represents.Fire Starter. The device produces a miniature flame, which you can use to light a candle, torch, or campfire. Using the device requires your action.Music Box. When opened, this music box plays a single song at a moderate volume. The box stops playing when it reaches the song’s end or when it is closed.

Hurgon
Dwarves of Hurgon have spent time in the deep dark recesses of the world and have been touched by shadows in the process.
[These dwarves are based on Shadow Dwarves mentione by Bruce Heard from http://bruce-heard.blogspot.com/2012/06 ... world.html. I want them to have some ability related to shadows, but haven't figures out what that might be yet.]

Ability Score Increase. Your Wisdom score increases by 1.

Darkvision. Accustomed to life underground, you have superior vision in dark and dim conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.

[Some additional Shadow based ability needed]

Karlheig
Karlheig dwarves are intelligent and introspective. They are known as philosophers, thinkers, and innovators.
[These dwarves have been heavily influenced by the kopru, and as such possess some form of mental/psionic abilities. Right now I'm representing that with a single Psionic Aptitude, but that may change based on feedback.]